RI/FS & Remedial Design

Most of the experts at SSP&A were involved in groundwater long before it became a focus of environmental compliance programs. However, throughout the development of compliance programs, SSP&A has been actively involved in applying groundwater and environmental science to the resolution of problems within the regulatory framework.

SSP&A is providing ongoing services as the lead hydrogeological consultant for the groundwater operable unit of the FAR-MAR-CO subsite of the Hastings groundwater contamination site. SSP&A completed a remedial investigation of the FAR-MAR-CO subsite in 1993. Subsequently, SSP&A developed a Focused Feasibility Study (FFS), and Engineering Evaluation/Cost Analysis (EECA) Report that established plans for an innovative Interim Remedy for groundwater collection and treatment. Since implementation of that remedy (1996/1997), SSP&A has overseen collection and interpretation of monitoring data, and been the primary technical contact for USEPA's concerns. At the current time, the Final Remedy is being implemented.

Carbon tetrachloride (CT) and ethylene dibromide (EDB) were released to soil and groundwater at the FAR-MAR-CO subsite due to the use of grain fumigants from the 1950s to 1970s. The resultant plumes of groundwater contamination extend for more than two miles downgradient within an alluvial sole-source aquifer of the high plains. The CT and EDB commingle with other contaminants, primarily TCE, that originated from other subsites of the Hastings groundwater contamination site. The scarcity of water in Nebraska necessitated an interim remedy that maximized the water's value, while still providing an effective collection and treatment system. The solution promoted by SSP&A in the 1993 FFS and EECA was to utilize the cooling tower of an existing coal-fired power plant as an air-stripper for contaminated groundwater extracted from a newly installed remediation well. Since 1997, the plume has been contained through groundwater extraction, primarily at "Well D." After piping to the Whelan Energy Center, the contaminated water is used as non-contact cooling water, and then sent to the cooling tower for treatment and discharge to the atmosphere.

In 2007, SSP&A submitted to USEPA a Feasibility Study for the final subsite remedy. Incorporated into this FS are groundwater flow and contaminant transport models developed with MODFLOW and MT3D, respectively. Following the 2009 approval of the Final Remedy Record of Decision, SSP&A has been implementing its required elements. The primary treatment of the groundwater remedy remains pumping and treating through the Well D – Whelan Energy Center System. Additional elements have included a transect of direct-push groundwater sampling locations to further delineate vertical boundaries of the groundwater contamination and installation additional nested groundwater monitoring wells using sonic drilling methods. In addition, SSP&A has completed a Source Area Enhanced Bioremediation project that included subsurface injection of emulsified vegetable oil (EVO) to assist in degradation of CT and EDB in the source area.

Lone Pine Landfill - Freehold, New Jersey

A remedial investigation and feasibility study was performed for the off-site area surrounding the Lone Pine Landfill. During the remedial investigation, field investigations were performed, and the data were analyzed to describe the hydrogeologic and chemical systems. Assessments of the extent and magnitude of existing contamination in the off-site area and of the potential for migration of this contamination in the ground and surface-water systems outside the landfill were conducted. In the feasibility study, potential remedial alternatives for the off-site area were evaluated in detail. A three-dimensional groundwater flow model was used to predict the effects of the various potential remedial actions on the hydrogeologic system.

Remedial alternatives that were considered and modeled included a slurry wall with french drain and impermeable cap, combined with various arrays of injection and extraction wells and interceptor trenches. A particle-tracking method was used in conjunction with the flow model to describe the direction and rates of groundwater flow associated with each simulation. A mixed linear-reservoir model was used to estimate the time required to achieve remedial goals for site clean-up. In addition, a study of the nature and volume of fluids at the site was completed to aid in the design of a leachate treatment system. SSP&A prepared all the documents required as part of the RI/FS process and participated in negotiations with the regulatory agencies for selection of the final remedy.

1990 Bay Road Site - East Palo Alto, California

The Rhone-Poulenc/Sandoz 1990 Bay Road site was used for the formulation of arsenic-based pesticides for over a half-century. As a result of these activities, soils and groundwater in the vicinity of the site contain very high concentrations of arsenic and related inorganic compounds. SSP&A has managed the ongoing RI/FS process for this site since the early 1980s. Since large volumes of contaminated soil and groundwater at this site rendered complete clean-up extremely expensive, SSP&A developed strong technical arguments to support limited removal and containment options. These options were aggressively and successfully defended before the regulatory agencies. The final remedy for the site involved removal and containment of contaminated soils, construction of a slurry wall for containment of the groundwater plume, and construction of an asphalt cap. The remedy has been partially implemented with soil removal and stabilization completed in 1991.

Stringfellow Site - Glen Avon, California

The Stringfellow Hazardous Waste Site is located within the Glen Avon Basin, a segment of the Chino groundwater basin, in Riverside County, California, approximately 50 miles east of Los Angeles. The original disposal area is located at the head of Pyrite Canyon in the southern portion of the Jurupa Mountains where five hydrostratigraphic units have been identified onsite. The disposal area was operated as a Class I industrial waste disposal facility from 1956 through 1972 on land owned by the Stringfellow Quarry Company. Approximately 34 million gallons of industrial process wastes containing spent acids and caustics, solvents, pesticide by-products, metals and other inorganic and organic contaminants were discharged into evaporation ponds onsite during this period. Because the site is geographically separated into four contaminant zones, site characterization, groundwater modeling, and development and implementation of remediation plans required careful attention due to the hydrologic, geographic, and contaminant complexities at this site. The primary contaminants of concern included TCE, chloroform, nitrates, and sulfates.

SSP&A acted as principal technical advisor on groundwater issues, oversaw field investigations, and evaluated remedial activities. SSP&A was initially retained as groundwater advisor by the Possible Responsible Parties (PRP) group to respond to the California Department of Health Services' contractor’s Remedial Investigation/Feasibility Study (RI/FS). Based on a review of the RI/FS and supportive data, SSP&A was able to demonstrate that the FS groundwater remediation plans were not feasible. SSP&A’s role was expanded to include conducting a feasibility study to identify potential remediation alternatives; conducting hydrogeologic investigations; performing flow and transport modeling; providing expert testimony regarding the nature and extent of site contamination and investigative programs; participating in technical presentations to the PRP group and government agencies; and providing oversight and evaluation of continuing work performed by state agencies. SSP&A developed alternative groundwater remediation scenarios for both on-site and off-site contamination. Remedial measures included groundwater extraction (onsite wells and drains), onsite pre-treatment of metals and organics followed by treatment in Orange County POTW and discharge into the Pacific Ocean.

Kodak Park - Rochester, New York

Kodak Park is a 2,000 acre photographic manufacturing facility that has been in operation since the late 1800's. SSP&A conducted a Corrective Measure Study for a portion of the park which was devoted primarily to chemical manufacturing and silver recovery. The study considered the need for soil and groundwater remediation in the site area and developed remedial alternatives. Groundwater contamination at the site is characterized by dissolved volatile organic compounds and DNAPL in fractured bedrock. Groundwater flow is controlled to a large extent by a network of industrial sewers which drain groundwater from the site, and by a 16-foot diameter tunnel located about 100 feet below land surface which was built by the City of Rochester to provide for storm-water overflow. SSP&A prepared a Corrective Measure Study report for the considered portion of Kodak Park; the report was submitted to the State in late 1994.

One Briggs Drive, East Greenwich, Rhode Island

SSP&A worked in association with Treadwell and Rollo, Inc. to perform a remedial investigation of a former waste-disposal area located at a Stanley-Bostitch manufacturing facility near East Greenwich, Rhode Island. Waste materials, including VOCs, were disposed of in lagoons located in overburden materials. Field studies were performed and a remedial design developed to contain contamination in the overburden and granitic bedrock underlying the overburden. The remedial design included a 2,300-foot long subdrain completed to the base of the overburden materials with several shallow extraction wells completed in the bedrock. Several remedial designs were evaluated using a calibrated groundwater flow model developed by SSP&A.

Martin-Marietta Facility - Denver, Colorado

SSP&A developed a linked groundwater and surface water flow model for the shallow alluvial aquifer, the Pierre Shale and other dipping bedrock units to evaluate the fate and transport of VOCs, metals, and other contaminants from onsite manufacturing areas to the downgradient river alluvium and the South Platte River. SSP&A used the model to evaluate the risk to Denver municipal wells located in the river alluvium and to evaluate the effectiveness of existing interim groundwater interception measures. SSP&A also performed modeling and fate and transport evaluations to evaluate alternate groundwater remedial measures and determine optimal well locations in alluvial channels for expediting the clean-up. SSP&A provided these technical services to complement engineering services provided by another consultant retained by the facility in the conduct of the RI/FS.

Investigation and Remediation of a Gasoline Spill, Virginia

During the construction of a housing subdivision, a 32-inch underground gasoline pipeline was ruptured and over 15,000 gallons of unleaded gasoline spilled. A significant portion of the total was unaccountable and presumed to have infiltrated the surrounding soils. SSP&A conducted both soil-gas and groundwater investigations to determine the extent and distribution of contamination. The majority of the gasoline was found to be held by the materials above the water table. SSP&A designed, installed, and operated three vapor extraction systems with a total of 50 extraction wells to remediate areas affected by the contaminated soil. To monitor potential health risks to residents in surrounding housing units, 66 soil-gas monitoring tubes were also installed and were sampled periodically. The vapor extraction system recovered vapor equivalent to over 5,000 gallons of gasoline before Fairfax County, Virginia, deemed the site fully remediated.

Acidic Tailings Pile Seepage Attenuation Model, Western US

For a private client involved in litigation, SSP&A has developed a hydrogeochemical equilibrium model which incorporates groundwater flow to predict the attenuation of toxic metals from acidic tailings-pile seepage. The major processes responsible for the attenuation of the contaminants are dilution by underlying groundwater, hydrodynamic dispersion, sorption, precipitation, and co-precipitation. The computer code PHREEQM was used to simulate aqueous mixing, chemical reaction, and the transport of tailings leachate in an alluvial matrix. Adsorption of metal cations was simulated using ion-exchange reactions. The adsorption and attenuation of arsenate was predicted using the surface complexation models incorporated into the computer code HYDRAQL, a chemical equilibrium model. The attenuation of metals within a short distance from the tailings piles was predicted by the models and the model predictions are supported by field observations of the site.